Transistor and semiconductor device

ABSTRACT

A transistor is provided, which is entirely and partially transparent by the use of a transparent channel layer made of zinc oxide or the like. A channel layer  11  formed of a transparent semiconductor such as zinc oxide ZnO. A transparent electrode is used for all of a source  12 , a drain  13  and a gate  14 , or a part of them. As the transparent electrode, a transparent conductive material such as conductive ZnO doped with, for example, group III elements is used. As a gate insulating layer  15 , a transparent insulative material such as insulative ZnO doped with elements capable of taking a valence of one as a valence number or group V elements is used. If a substrate  16  must be transparent, for example, glass, sapphire, plastic or the like can be used as a transparent material.

FIELD OF THE INVENTION

The present invention relates to a transistor and a semiconductordevice, more particularly to a transparent transistor, a semiconductordevice having the transparent transistor stacked thereon, and asemiconductor device to which the transparent transistor is applied fordriving a light emission device, for reading/writing data from/to amemory, and for other purposes. It should be noted that in the presentinvention, a concept of “transparent” includes a concept of “beingtransparent or offering light transmission property” for the sake ofsimplifying descriptions.

DESCRIPTIONS OF THE RELATED ARTS

A thin film transistor using amorphous silicon, polycrystalline siliconor the like has been generally used as a transistor for use in drivingliquid crystal display devices. Since these materials exhibitphotosensitivity for the visible light region, carriers are generated bya beam of light, and resistivity of a thin film constituting the thinfilm transistor is lowered. For this reason, when the beam of light isradiated thereonto, the transistor may be made to be a turn-on state, inspite of the fact that the transistor must be controlled to be aturn-off state. Accordingly, to keep the transistor at the turn-onstate, the lowering of the carrier resistivity of the thin film due tothe radiation of the beam of light has been heretofore prevented by theuse of a light shielding layer made of a metal film or the like.

DISCLOSURE OF THE INVENTION

Generally, the liquid crystal display device has been widely used for anotebook type personal computer or the like, and an energy-savingmeasure, a high luminance and a miniaturization have been requested ofthe liquid crystal display device. To reply to these requests, it iseffective to increase a rate of an effective area of a display portionwithin a unit pixel. However, since a light shielding layer made of ametal thin film or the like in the transistor for driving the liquidcrystal display device is formed as described above, a rate of an areaof a light transmission portion to that of the light shielding layer(opening ratio) in the pixel reduces. Accordingly, a reduction of atransistor area by improving a performance of the transistor or animprovement of luminance of a backlight are necessary to develop adisplay device having high luminance. However, the measure to improvethe characteristic of the transistor shows a limitation to a yield,leading to an increase in cost. Moreover, the measure to improve theluminance of the backlight increases an amount of energy consumption.

From the viewpoint of the above described points, the object of thepresent invention is to provide a transistor using a transparent channellayer made of zinc oxide or the like, which is transparent partially orentirely, because an orientation control of the zinc oxide and a valenceelectron control thereof that has been heretofore difficult is nowpossible. Specifically, the object of the present invention is toprovide a transistor which uses a transparent material such as the zincoxide or the like for a channel layer (conductive layer) so that thechannel layer does not have a photosensitivity for the visible lightregion, and removes a necessity to form a light shielding layer, thusincreasing an area rate of a display portion of a liquid crystal displaydevice or the like.

Furthermore, the object of the present invention is to use a transparenttransistor for various kinds of applications in an optical device fieldfor use in driving a light emission device such as a plane lightemission laser and an electroluminescence device and for use in amemory. Still furthermore, the object of the present invention is toprovide a semiconductor device used as a transparent electronic devicefor various kinds of wide applications in addition to a driving circuitrequiring no light shielding layer.

According to first solving means of the present invention, a transistoris provided, which comprises:

-   -   a transparent channel layer using any one of zinc oxide ZnO,        zinc magnesium oxide Mg_(x)Zn_(1-x)O, zinc cadmium oxide        Cd_(x)Zn_(1-x)O and cadmium oxide CdO; and    -   a source, a drain and a gate in which a transparent conductive        material such as conductive ZnO doped or undoped with any one of        group III elements, group VII elements, group I elements and        group V elements, a transparent conductive material such as        In₂O₃, SnO₂ and (In—Sn)O_(x), or an untransparent electrode        material are used partially or entirely.

According to second solving means of the present invention, a transistoris provided,

-   -   which comprises:    -   an emitter and a collector, or a base which are made of a        transparent n-type semiconductor such as ZnO doped with group        III elements or group VII elements;    -   a base, or an emitter and a collector which are made of a        transparent p-type semiconductor such as ZnO doped with group I        element or group V elements; and    -   a base electrode, an emitter electrode and a collector electrode        respectively formed on the base, the emitter and the collector,        in which a transparent conductive material such as conductive        ZnO doped or undoped with any one of group III elements, group        VII elements, group I elements and group V elements, a        transparent conductive material such as InO₃, SnO₂ and        (In—Sn)O_(x), or an untransparent electrode material are used        partially or entirely.

Still another object of the present invention is to provide asemiconductor device in which a transparent transistor is stacked, and asemiconductor device applied to a light emission device, a memory or thelike.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIGS. 1(A) and 1(B) are section views of a first embodiment of atransistor according to the present invention.

FIGS. 2(A) and 2(B) are section views of second and third embodiments ofa transistor according to the present invention.

FIG. 3 is a section view of a fourth embodiment of a transistoraccording to the present invention.

FIG. 4 is a section view of a fifth embodiment of a transistor accordingto the present invention.

FIG. 5 is a section view of a stacked type semiconductor device.

FIGS. 6(A) and 6(B) are a section view and a circuit diagram of asemiconductor device to which a FET according to the present inventionis applied for driving a light emission device.

FIGS. 7(A) and 7(B) are a section view and a circuit diagram of asemiconductor device to which a bipolar transistor according to thepresent invention is applied for driving a light emission device.

FIGS. 8(A) and 8(B) are a section view and a circuit diagram of a deviceto which the FET according to the present invention is applied forcontrolling a memory device.

FIG. 9 is a characteristic view of a transistor of the presentinvention.

PREFERABLE EMBODIMENTS OF THE INVENTION

(1) Field Effect Transistor (FET)

A section view of a first embodiment of a transistor according to thepresent invention is shown in FIGS. 1(A) and 1(B). As shown in FIG.1(A), the transistor of the first embodiment relates to a FET, andcomprises a channel layer 11, a source 12, a drain 13, a gate 14, a gateinsulating layer 15 and a substrate 16. The channel layer 11 is formedon the substrate 16. On the channel layer 11, formed are the gateinsulating layer 15, the source 12 and the drain 13. The gate 14 isformed on the gate insulating layer 15.

A modification of a first embodiment is shown in FIG. 1(B). In thistransistor, the channel layer 11 is formed on the substrate 16.Furthermore, on the channel layer 11, the source 12 and the drain 13 areformed by an ohmic junction, and the gate 14 is formed thereon by aShottky junction. In this embodiment, since the transistor lacks thegate insulating layer 15 unlike that of FIG. 1(A), a proper gap isprovided between the gate 14 and the source 12 and between the gate 14and the drain 13.

Materials of the respective constituent components will be describedbelow.

Firstly, the channel layer 11 is formed of a transparent semiconductor.As the material of the transparent channel layer 11, any of zinc oxideZnO, zinc magnesium oxide Mg_(x)Zn_(1-x)O zinc cadmium oxideCd_(x)Zn_(1-x)O, cadmium oxide CdO or the like can be used. Either amaterial doped with n and p-type impurities or a material undoped withthem may be used.

Secondly, a transparent electrode is used either for all of the source12, the drain 13 and the gate 14 or for any of them. As the transparentelectrode, a transparent conductive material such as conductive ZnO isused, which is doped with any one of group III elements (B, Al, Ga, In,Tl), group VII elements (F, Cl, Br, I), group I elements (Li, Na, K, Rb,Cs) and group V elements (N, P, As, Sb, Bi) or undoped with them.Herein, when these elements are doped, a doping amount can be setproperly. For example, though n⁺⁺-ZnO doped with n-type elements at ahigh concentration can be used, elements to be doped are not limited tothis. Moreover, as the source 12, the drain 13 and the gate 14,transparent conductive materials such as In₂O₃, SnO₂ and (In—Sn)O_(x)can be used in addition to these. Besides these transparent materials,metals such as Al and Cu and electrode materials such as highly dopedsemiconductor polysilicon which is untransparent may be used. Moreover,it is possible to adopt a transparent material and a non-transparentmaterial together.

Thirdly, as the gate insulating layer 15, a transparent insulatingmaterial such as insulative ZnO doped with an element which can take avalence of 1 as a valence number or doped with group V element is used.As the element which can take the valence of 1, for example, group Ielements (Li, Na, K, Rb, Cs), Cu, Ag, Au or the like are enumerated. Asthe group V element, N, P, As, Sb, Bi or the like are enumerated. As thegate insulating layer 15, in addition to these materials, a transparentinsulative oxide material such as Al₂O₃, MgO, CeO₂, ScAlMgO₄ and SiO₂can be used. Furthermore, a transparent insulator such as vinyl andplastic may be used. It should be noted that the gate insulating layer15 is preferably made of a high insulative material offering a goodlattice matching with the material of the channel layer 11. If thechannel layer 11 is made of zinc oxide, for example, ScAlMgO₄ or thelike are used. These materials are in conformity with each other intheir lattice constants in all planes thereof within 1%, and thesematerials can be epitaxilally grown mutually. Moreover, by using a highdielectric material for the gate insulating layer 15, it is alsopossible to allow the transistor itself to possess a memory function. Asthe high dielectric material, for example, Zn_(1-x)Li_(x)O,Zn_(1-x)(Li_(y)Mg_(x-y))O or the like can be used.

Fourthly, as the substrate 16, insulative materials are mainly used.When it is intended that the substrate is made to be transparent, forexample, glass, sapphire, plastic or the like can be used as atransparent material. Furthermore, materials that are untransparent maybe used as the substrate depending on purposes. For example, for thepurposes in which transparency is required as a liquid crystal displayscreen or the like, a transparent substrate should be used. When a zincoxide single crystal or a ScAlMgO₄ single crystal as one of materialshaving the most excellent property is used for the substrate 16, thetransparent channel layer 11, or the source 12 and the drain 13 can begrown epitaxially on the substrate. Although some grain boundaries existon the substrate made of a sapphire single crystal, it is possible togrow the channel layer 11 or the like epitaxially. Moreover, by usingthe glass substrate, though an in-plane orientation is random, it ispossible to control the orientation in a thickness direction as c-axis,and the transistor of this embodiment can show sufficientcharacteristics as a driving circuit of a display device.

In FIGS. 2(A) and 2(B), section views of second and third embodiments ofa transistor according to the present invention are shown. Thetransistor of the second embodiment shown in FIG. 2(A) relates to a FET,and comprises a channel layer 21, a source 22, a drain 23, a gate 24, agate insulating layer 25 and a substrate 26. The source 22 and the drain23 are formed on the substrate 26. The channel layer 21 is formed so asto cover the substrate 26, the source 22 and the drain 23. The gateinsulating layer 25 is formed on the channel layer 21. The gate 24 isformed on the gate insulating layer 25. Herein, the gate 24, the gateinsulating layer 25 and the channel layer 21 constitute a MIS structure.

A section view of the third embodiment of the transistor according tothe present invention is shown FIG. 2(B). This transistor is amodification of the second embodiment. In the transistor shown in FIG.2(B), the gate insulating layer 25 is not formed unlike the transistorshown in FIG. 2(A), and the gate 24 and the channel layer 21 constitutesa Shottky junction structure. When the gate insulating layer 25 isprovided like the transistor shown in FIG. 2(A), a limitation to avoltage applied to the gate is small. Contrary to this, when the gateinsulating layer 25 is not provided like the transistor shown in FIG.2(B), withstand voltages between the gate and the source and between thegate and the drain become low. In this case, manufacturing processes aresimplified.

A section view of a fourth embodiment of a transistor according to thepresent invention is shown in FIG. 3. The transistor of the fourthembodiment relates to a FET, and comprises a channel layer 31, a source32, a drain 33, a gate 34, a gate insulating layer 35 and a substrate36. The channel layer 31 is formed on the substrate 36. The gateinsulating layer 35 is formed on the channel layer 31, and the gate 34is formed on the gate insulating layer 35. The source 32 and the drain33 can be formed by diffusing or ion-implanting impurities thereintousing the gate insulating layer 35 as a mask. Moreover, as amodification of this embodiment, the gate insulating layer 35 can beomitted by appropriately setting a size of the gate 34 to a certainscale.

It should be noted that in the foregoing second to fourth embodiments,materials of the constituent components are the same as those describedin the first embodiment.

(2) Bipolar Transistor

A section view of a fifth embodiment of a transistor according to thepresent invention is shown in FIG. 4. The transistor of the fifthembodiment relates to a bipolar transistor, and comprises a base 41, anemitter 42, a collector 43, a base electrode 44, an emitter electrode45, a collector electrode 46 and a substrate 47.

In an npn-type transistor, the emitter 42 and the collector 43 areformed of an n-type transparent semiconductor, and the base 41 is formedby a p-type transparent semiconductor. The base electrode 44, theemitter electrode 45 and the collector electrode 46 are formedrespectively on the base 41, the emitter 42 and the collector 43.Similarly, in a pnp-type transistor, the emitter 42 and the collector 43are formed of a p-type semiconductor as shown in parentheses, and thebase 41 is formed of an n-type transparent semiconductor. Since thebipolar transistor can allow a large current to flow therethroughcompared to the FET, the bipolar transistor is particularly advantageouswhen a large current is required for driving a laser or the like.

The materials of the constituent components will be described below.

As the n-type transparent semiconductor, for example, n-type ZnO isused. The n-type ZnO is ZnO doped with, for example, group III elements(B, Al, Ga, In, TI), group VII elements (F, Cl, Br, I). As the p-typetransparent semiconductor, for example, p-type ZnO is used. The p-typeZnO is ZnO doped with, for example, group I elements (Li, Na, K, Rb, Cs)and group V elements (N, P, As, Sb, Bi). A doping amount can be set to aproper value depending on a dimension of the device, a thicknessthereof, an integration degree thereof and performance thereof.

Materials of the base electrode 44, the emitter electrode 45, and thecollector electrode 46 are the same as those of the source 12, the drain13 and the gate 14 described in the first embodiment. Specifically, asthe transparent electrode, a transparent conductive material such asconductive ZnO doped with any one of group III elements (B, Al, Ga, In,Ti), group VII elements (F, Cl, Br, I), and group I elements (Li, Na, K,Rb, Cs) or conductive ZnO undoped with these materials is used. Herein,when these elements are doped, it is possible to set a doping amount toa proper value. Although n⁺⁺-ZnO or the like, which are doped withn-type elements with a high concentration, can be used, the dopingamount is not limited to this. Moreover, as the base electrode 44, theemitter electrode 45 and the collector electrode 46, a transparentconductive material such as In₂O₃, SnO₂ and (In—Sn)O_(x) can be used inaddition to the above described materials. Besides the transparentmaterials, a metal such as Al and Cu and an untransparent electrodematerial such as highly doped semiconductor polysilicon may be used.Moreover, transparent or untransparent materials are properly selectedand used for all of the electrodes or a part of them.

(3) Stacked Type Semiconductor Device

A section view of a stacked type semiconductor device is shown in FIG.5. FIG. 5 shows, as an example, a case where the transistors of thefirst embodiment are stacked. Specifically, a second transistor isfurther formed on a transistor which comprises a channel layer 11, asource 12, a drain 13, a gate 14, a gate insulating layer 15 and asubstrate 16. At this time, an insulating layer 57 and a conductiveshielding layer 58 are formed between the first and second transistors.The conductive shielding layer 58 serves to electrically shield thefirst and second transistors from one another. As the second transistor,an insulating layer 59 serving as a substrate is formed, and a secondsource 52 and a second drain 53 are formed thereon. Moreover, a secondchannel layer 51 is formed so as to cover the insulating layer 59, thesecond source 52 and the second drain 53, and a second gate insulatinglayer 55 and a second gate 54 are formed thereon.

Materials of the insulating layers 57 and 59 may be the same as that ofthe gate insulating layer 15, and another insulating material identicalto that of the transparent substrate 16 may be used. As a material ofthe conductive shielding layer 58, the same material as that of thesource 12, the drain 13 and the gate 14 can be used. By forming theinsulating layer 57 or 59 so as to have a thickness larger than that ofeither the channel layer 11 or the channel layer 11 and the gateinsulating layer 15, the conductive shielding layer 58 and theinsulating layer 57 or 59 can be omitted.

When the transistors are stacked upon another, the channel layer 11, thesecond channel layer 51 or the insulating layer 57 is preferablyflattened suitably according to demand. Note that since there is apossibility of increasing cost by adding flattening processes, any ofthese layers may be flattened properly. Furthermore, as to the number ofthe stacked transistors, the suitable number of the transistors can bestacked according to demand. Furthermore, the transistors of theforegoing first to fifth embodiments are suitably selected and can bestacked. Still furthermore, the plural kinds of transistors may beselected to be stacked mixedly upon another.

(4) Application to Light Emission Device

A section view and a circuit diagram of a semiconductor device to whichthe FET according to the present invention is applied for driving alight emission device are shown in FIGS. 6(A) and 6(B). Referencesymbols a, b and c in the section view of FIG. 6(A) correspond toreference symbols a, b and c in the circuit diagram of FIG. 6(B). Inthis device, a transistor is formed of a channel layer 61, a source 62,a drain 63, a gate 64, a gate insulating layer 65 and a substrate 66. Asemiconductor layer 67 is formed on the region of the drain 63, wherebythe drain 63 and the semiconductor layer 67 form a light emissionportion. Moreover, a source electrode 68, a gate electrode 69 and alight emission portion electrode 60 are provided in this device. As tothe light emission portion, when an n-type semiconductor is used for thedrain 63, a p-type semiconductor is used for the semiconductor layer 67.On the other hand, when a p-type semiconductor is used for the drain 63,an n-type semiconductor is used for the semiconductor layer 67.

A transparent semiconductor material identical to that of the gate 64 isused for the semiconductor layer 67, and a transparent electrodematerial is used for the light emission portion electrode 60. Thus, thelight emission portion of this device is enabled to perform a planelight emission in the upward direction in FIG. 6(A). Furthermore, byusing a transparent material for the substrate 66, the light emissionportion thereof is enables to perform the plane light emission in thedownward direction in FIG. 6(A). In addition, if a light emission zoneis equal to an ultraviolet zone, a light emitted from the light emissionportion can be converted into a visible light by disposing fluorescentsubstance either on the light emission portion or under the lightemission portion, in other words, on the semiconductor layer 67 and thelight emission portion electrode 60 or under the substrate 66.

A section view and a circuit diagram of a semiconductor device to whichthe bipolar transistor according to the present invention is applied fordriving a light emission device are shown in FIGS. 7(A) and 7(B).Reference symbols a, b and c in the section view of FIG. 7(A) correspondto reference symbols a, b and c in the circuit diagram of FIG. 7(B). Inthis device, a transistor is formed of a base 71, an emitter 72, acollector 73, a base electrode 74, a collector electrode 76 and a base77. Furthermore, a semiconductor layer 78 is formed on a region of theemitter 72, whereby the emitter 72 and the semiconductor layer 78 form alight emission portion. In addition, a light emission portion electrode79 is formed on the semiconductor layer 78. When an n-type semiconductoris used as the emitter 72, a p-type semiconductor is used for thesemiconductor layer 78. On the other hand, when a p-type semiconductoris used as the emitter 72, an n-type semiconductor is used for thesemiconductor layer 78.

The light emission portion is enabled to perform a plane light emissionin the upward direction in FIG. 7(A) by using a transparentsemiconductor material identical to that of the base 71 for thesemiconductor layer 78 and a transparent electrode material for thelight emission portion electrode 79. Moreover, by using a transparentmaterial for the substrate 77, the light emission portion is enabled toperform a plane light emission in the downward direction in FIG. 7(A).If a light emission zone is equal to an ultraviolet zone, a lightemitted from the light emission portion can be converted into a visiblelight by disposing a fluorescent substrate on the light emission portionor under the light emission portion, in other words, on thesemiconductor layer 78 and the light emission portion electrode 79 orunder the substrate 77.

It should be noted that the transistors of the first to thirdembodiments can be combined with each other for use in driving byforming a light emission portion. Moreover, in the foregoingdescriptions, a region continuous with the source or the drain (thecollector or the emitter) is used in a part of the light emissionportion. In addition to this, a different semiconductor regioncontinuous with the source or the drain (the collector or the emitter)is formed, and this region may be used as a part of the light emissionportion. Moreover, the light emission portion may be a light-emittingdiode or a laser diode, and a proper light emission device can beformed. Moreover, when the present invention is applied, a semiconductordevice, which is entirely transparent, can be fabricated by driving atransparent ZnO light emission device by the use of the transparenttransistor. The light emission device can also be made to be partiallytransparent.

As the light emission portion, proper structures such as a multilayeredreflection film, a double hetero structure and a plane light emissionstructure are adopted, and they can be combined with each other.Moreover, a plurality of the light emission portions and the transistorsare arranged in a matrix fashion, and each of the light emissionportions is driven by the transparent transistor, whereby the lightemission portion can be applied to a display, an illumination panel, apartial light adjusting panel or the like suitably.

(5) Application to Memory

A section view and a circuit diagram of a device in which the FETaccording to the present invention is applied to a control of a memorydevice are shown in FIGS. 8(A) and 8(B). Reference symbols a, b and c ofFIG. 8(A) correspond to reference symbols a, b and c of FIG. 8(B). Inthis device, a transistor is formed of a channel layer 81, a source 82,a drain 83, a gate 84, a gate insulating layer 85 and a substrate 86. Onthe source 82, formed is a conductive layer 88 made of a transparentconductive material identical to that of the source 82. Furthermore, ona region of the drain 83, formed is a semiconductor layer or aconductive layer 87 with the gate insulating layer 85 interposedtherebetween, and thus these constituent components form a capacitor.Herein, though the gate insulating layer 85 is used as aninter-electrode insulator of the capacitor, a different insulating layerfrom this gate insulating layer 85 may be formed to be used.Furthermore, as an electrode of the capacitor, a region continuous tothe source or the drain may be used, or alternatively anothersemiconductor region or another conductive region, which is connected tothe source or the drain, may be used. An electrode material forming thecapacitor may be a transparent material or an untransparent material,and the transparent material may be partially used for the electrodematerial of the capacitor. By properly using the transparent materialfor these layers and these regions, it is possible to fabricate a memorydevice which is entirely transparent or partially transparent.

Also when the bipolar transistor according to the present invention isused, the application to the memory device is possible by forming acapacitor on the substrate properly. Specifically, for example, in thebipolar transistor as in the foregoing embodiments, a capacitor can beformed of a region continuous to the collector or the emitter or aregion of another semiconductor or another conductor connected to thecollector or the emitter, the insulating layer on this region, and thesemiconductor layer or the conductive layer on the insulating layer.

When the bipolar transistor is applied to the memory device, the memorydevice can be realized by arranging the transistors and the capacitorsin a matrix fashion and by driving the capacitors by the correspondingtransistors.

(6) Characteristics

An example of the characteristic view of the transistor according to thepresent invention is shown in FIG. 9. FIG. 9 shows an example of achange in a drain current (axis of ordinates) with regard to the FETusing ZnO for the channel layer when a drain current (axis of abscissa)is changed in the first embodiment of the present invention. Herein, athickness of the ZnO channel layer was set to 200 nm, a thickness of thegate insulating layer was set to 100 nm, a gate length was set to 600μm, and a gate width was set to 200 μm. A gate voltage V_(G) was set to0 V and a range from −0V to −8V.

(7) Other Applications

The transistor of the present invention can be fabricated on the samesubstrate together with the light emission device, the capacitor andother devices. Moreover, the same kind of transistor or different kindsof transistors of the present invention are formed, and transparentmaterials can be used for wiring between the transistors. Thetransistors and the devices driven by these transistors can be formed soas to be entirely or partially transparent properly. Moreover, a size, athickness and a dimension of the transistor can be properly set inaccordance with purposes, processes or the like. A doping amount can beproperly set in accordance with manufacturing processes, deviceperformance or the like according to demand.

Furthermore, as a transparent n-type semiconductor, a transparent n-typesemiconductor, a transparent conductive material and a transparentinsulating material, the example in which elements are doped on thebasis of the ZnO semiconductor was described. However, the presentinvention is not limited to this. For example, besides zinc oxide ZnO,elements may be doped on the basis of a transparent material such aszinc magnesium oxide Mg_(x)Zn_(1-x)O, zinc cadmium oxideCd_(x)Zn_(1-x)O, cadmium oxide CdO or the like properly.

Besides the foregoing ways, it is possible to realize a semiconductordevice which is entirely or partially transparent by applying to atransistor performing signal processing by driving a detector fordetecting light ranging from ultraviolet zone to X-ray zone, to anoxygen sensor, and to a device obtained by combining a sound wave,Surface Acoustic Wave (SAW) or piezoelectric property. Moreover, thepresent invention enables an electronic circuit to attach on a windowglass of a car, a house or the like, a transparent plastic board or thelike. The present invention can manufacture computer peripheralequipment for example, a keyboard, a touch panel and a pointing deviceso as to be transparent. By being transparent, they can be manufacturedconfidentially, or they can be manufactured so as to be hard to lookfrom some other place. Moreover, it is possible to propose somethingoriginal in terms of design. In addition to these, an application rangeof the present invention is very wide.

Industrial Applicability

The present invention can provide the transistor using the transparentchannel layer made of zinc oxide or the like, which is entirely orpartially transparent. Specifically, according to the present invention,by using the transparent material such as zinc oxide or the like for thechannel layer (conductive layer), the transistor can be provided, whichoffers no light sensitivity within the visible light region, thusremoving a necessity to form the light shielding layer, and increasesthe area rate of the display portion of the liquid crystal displaydevice or the like.

Furthermore, according to the present invention, the transparenttransistor can be used for various kinds of applications in an opticaldevice field for use in driving a light emission device such as a planelight emission laser and an electroluminescence device and for use in amemory. Still furthermore, according to the present invention, thesemiconductor device can be provided, which is used as a transparentelectronic device for various kinds of wide applications in addition toa driving circuit requiring no light shielding layer.

1-6. (canceled)
 7. A transistor, comprising: an emitter and a collector,or a base made of a transparent n-type semiconductor comprising any oneof zinc oxide ZnO, zinc magnesium oxide MgxZn1-xO, zinc cadmium oxideCdxZn1-xO and cadmium oxide CdO doped with group III elements or groupVII elements; a base, or an emitter and a collector made of atransparent p-type semiconductor comprising any one of zinc oxide ZnO,zinc magnesium oxide MgxZn1-xO, zinc cadmium oxide CdxZn1-xO and cadmiumoxide CdO doped with group I elements or group V elements; and a baseelectrode, an emitter electrode and a collector electrode, in which (1)a transparent conductive material such as conductive ZnO doped orundoped with any one of group III elements, group VII elements and groupI elements, (2) a transparent conductor such as In2O3, SnO2 and(In—Sn)Ox, or (3) an untransparent electrode material are used partiallyor entirely, the base electrode, the emitter electrode and the collectorelectrode being respectively formed on said base, said emitter and saidcollector.
 8. A semiconductor device, comprising: the transistoraccording to claim 7; and a light emission portion formed of a regioncontinuous to said collector or said emitter of said transistor or aregion of another semiconductor connected to said collector or saidemitter, and a semiconductor layer joined to said region.
 9. Asemiconductor device, comprising: the transistor according to claim 7,and a capacitor formed of a region continuous to said collector and saidemitter of said transistor or a region of another semiconductor or aconductor connected to said collector or said emitter, an insulatinglayer on said region, and a semiconductor layer or a conductive layer onsaid insulating layer. 10-12. (canceled)
 13. A semiconductor device,comprising a plurality of transistors according to claim 7, and aninsulating layer, said insulating layer is between transistors of saidplurality of transistors; wherein said insulating layer comprises atransparent insulating material including at least one of insulative ZnOdoped with elements capable of taking a valence of one as a valencenumber or group V elements, a transparent insulating oxide, and atransparent insulator.
 14. A semiconductor device, comprising: aplurality of transistors according to claim 7; and wiring between saidplurality of transistors, wherein said wiring comprises a transparentconductive material including at least one of conductive ZnO doped orundoped with group III elements, group VII elements, group I elementsand group V elements, a transparent conductor comprising at least one ofIn₂O₃, SnO₂, and (In—Sn)O_(x), or a un-transparent electrode material.15. A semiconductor device, comprising: the transistor according toclaim 7; and an inductor comprising a transparent conductive material,said transparent conductive material comprising at least one ofconductive ZnO doped or undoped with group III elements, group VIIelements, group I elements and group V elements, and a transparentconductor comprising at least one of In₂O₃, SnO₂ and (In—Sn)O_(x).
 16. Asemiconductor device, wherein a plurality of the semiconductor devicesaccording to claim 8 are arranged in a matrix shape, and a capacitor ora light emission portion is driven by each transistor.
 17. Asemiconductor device, wherein a plurality of the semiconductor devicesaccording to claim 9 are arranged in a matrix shape, and a capacitor ora light emission portion is driven by each transistor.
 18. A method ofmaking a transistor, comprising: depositing an emitter and a collector,or a base, wherein said emitter and said collector, or said base aremade of a transparent n-type semiconductor comprising any one of ZnO,zinc magnesium oxide MgxZn1-xO, zinc cadmium oxide CdxZn1-xO, andcadmium oxide CdO, and said n-type semiconductor is doped with group IIIelements or group VII elements; depositing a base, or an emitter and acollector, wherein said base, or said emitter and said collector aremade of a transparent p-type semiconductor comprising at least one ofZnO, zinc magnesium oxide MgxZn1-xO, zinc cadmium oxide CdxZn1-xO, andcadmium oxide CdO, said p-type semiconductor doped with group I elementsor group V elements; and depositing a base electrode, an emitterelectrode and a collector electrode, wherein said base electrode, saidemitter electrode and said collector electrode comprise a transparentconductive material comprising conductive ZnO doped or undoped with anyone of group III elements, group VII elements and group I elements, or atransparent conductive material comprising at least one of In₂O₃, SnO₂and (In—Sn)O_(x), or an un-transparent electrode material and whereinsaid base electrode, said emitter electrode and said collector electrodeare respectively formed on said base, said emitter, and said collector.19. The transistor of claim 7, wherein said transparent n-typesemiconductor includes at least conductive ZnO doped with group IIIelements or group VII elements.
 20. The transistor of claim 7, whereinsaid transparent p-type semiconductor includes at least conductive ZnOdoped with group I elements or group V elements.
 21. The transistor ofclaim 7, wherein said transparent conductive material includes at leastone conductive ZnO undoped and conductive ZnO doped with at least one ofgroup III elements, group VII elements, and group I elements.
 22. Thetransistor of claim 7, wherein said transparent conductive materialincludes at least one of In₂O₃, SnO₂, and (In—Sn)O_(x).
 23. Thetransistor of claim 7, wherein said base is made of a transparent n-typesemiconductor.
 24. The transistor of claim 7, wherein said base is madeof a transparent p-type semiconductor.
 25. The method of claim 18,wherein said transparent n-type semiconductor includes at leastconductive ZnO doped with group III elements or group VII elements. 26.The method of claim 18, wherein said transparent p-type semiconductorincludes at least conductive ZnO doped with group I elements or group Velements.
 27. The method of claim 18, wherein said transparentconductive material includes at least one of conductive ZnO undoped andconductive ZnO doped with any one of group III elements, group VIIelements and group I elements.
 28. The method of claim 18, wherein saidtransparent conductive material includes at least one of In₂O₃, SnO₂,and (In—Sn)O_(x).
 29. The method of claim 18, wherein said base is madeof a transparent n-type semiconductor.
 30. The method of claim 18,wherein said base is made of a transparent p-type semiconductor.
 31. Amethod of making a transistor, comprising: providing an emitter and acollector, or a base, wherein said emitter and said collector, or saidbase are made of a transparent n-type semiconductor comprising at leastone of zinc oxide ZnO, zinc magnesium oxide MgxZn1-xO, zinc cadmiumoxide CdxZn1-xO, and cadmium oxide CdO, and said n-type semiconductor isdoped with at least one of group III elements and group VII elements;providing a base, or an emitter and a collector, wherein said base, orsaid emitter and said collector are made of a transparent p-typesemiconductor comprising at least one of zinc oxide ZnO, zinc magnesiumoxide MgxZn1-xO, zinc cadmium oxide CdxZn1-xO, and cadmium oxide CdO,and said p-type semiconductor is doped at least one of with group Ielements and group V elements; and providing a base electrode, anemitter electrode, and a collector electrode; wherein said baseelectrode, said emitter electrode, and said collector electroderespectively are formed on said base, said emitter, and said collector;wherein said base electrode, said emitter electrode, and said collectorelectrode comprise: (1) a transparent conductive material comprisingconductive ZnO that is undoped and conductive ZnO that is doped with atleast one of group III elements, group VII elements, and group Ielements; or (2) a transparent conductor comprising at least one ofIn2O3, SnO2, and (In—Sn)Ox; or (3) an un-transparent electrode material.32. A method of using a transistor, said transistor comprising: anemitter and a collector, or a base, wherein said emitter and saidcollector, or said base are made of a transparent n-type semiconductorcomprising any one of zinc oxide ZnO, zinc magnesium oxide MgxZn1-xO,zinc cadmium oxide CdxZn1-xO, and cadmium oxide CdO, and said n-typesemiconductor is doped with at least one of group III elements and groupVII elements; or a base, or an emitter and a collector, wherein saidbase, or said emitter and said collector are made of a transparentp-type semiconductor comprising any one of zinc oxide ZnO, zincmagnesium oxide MgxZn1-xO, zinc cadmium oxide CdxZn1-xO, and cadmiumoxide CdO, and said p-type semiconductor is doped with at least one ofgroup I elements and group V elements; a base electrode, an emitterelectrode, and a collector electrode; wherein said base electrode, saidemitter electrode, and the collector electrode are respectively formedon said base, said emitter, and said collector; wherein said baseelectrode, said emitter electrode, and said collector electrodecomprise: (1) a transparent conductive material comprising one ofconductive ZnO that is undoped and conductive ZnO that is doped with atleast one of group III elements, group VII elements, and group Ielements; or (2) a transparent conductor comprising at least one ofIn2O3, SnO2, and (In—Sn)Ox, or (3) an un-transparent electrode material;and said method comprising applying a voltage across at least oneelectrode of said transistor.
 33. A transistor, comprising: an emitterand a collector, or a base made of a transparent n-type semiconductor,said transparent n-type semiconductor comprising at least one of zincoxide ZnO, zinc magnesium oxide MgxZn1-xO, zinc cadmium oxide CdxZn1-xO,and cadmium oxide CdO, and said transparent n-type semiconductor isdoped with at least one of group III elements and group VII elements; abase, or an emitter and a collector made of a transparent p-typesemiconductor, said transparent p-type semiconductor comprising any oneof zinc oxide ZnO, zinc magnesium oxide MgxZn1-xO, zinc cadmium oxideCdxZn1-xO, and cadmium oxide CdO, and said transparent p-typesemiconductor is doped with at least one of group I elements and group Velements; and a base electrode, an emitter electrode, and a collectorelectrode; wherein said base electrode, said emitter electrode, and saidcollector electrode are respectively formed on said base, said emitter,and said collector; and wherein said base electrode, said emitterelectrode, and said collector electrode comprise: (1) a transparentconductive material comprising one of conductive ZnO that is un-dopedand conductive ZnO that is doped with at least one of group IIIelements, group VII elements, and group I elements; or (2) a transparentconductor comprising at least one of In2O3, SnO2, and (In—Sn)Ox; or (3)an un-transparent electrode material.